History, Implementation and Current Use of the IFCC-IUPAC's Nomenclature for Properties and Units (NPU) Terminology in Denmark, Norway and Sweden.

Electronic exchange of health care data demands code/terminology systems. In the Scandinavian countries, the IFCC-IUPAC's Nomenclature for Properties and Units (NPU) terminology is used for results in biochemistry, pharmacology, and immunology. Implementation, use and administration of NPU has differed between the countries despite similar health care and lab sectors. In Norway and in one Swedish region NPU - with supplementary SNOMED CT codes is also used for reporting results in microbiology. In Denmark and to some extent in Norway and Sweden NPU is also used for ordering tests. In Norway NPU (as part of NLK) has since 2018 been mandatory in requesting governmental reimbursement for laboratory tests. The numbers of national codes vary considerably (DAN: 303, NOR: 1612, SWE: 415). Furthermore, in Denmark >3500 local codes are used for requisition and to communicate more details with the analytical result than the NPU terminology allows. Also, in Norway the NPU codes are by many lab professionals considered insufficient for communicating all relevant information with results. However, the Norwegian reimbursement system has been a strong motivator for implementing international NPU codes. We find it necessary to add information about "how" a measurement is done to the information about "what" is measured in the laboratory report. Until this is settled otherwise, we suggest an increased pragmatism towards producing national codes including method specific information. Furthermore, we recommend that organisations responsible for classifications have heavy professional participation and decision-making competencies in order to lead and guide implementation and optimal use of the classifications.